The invention relates to firing mechanisms for firearms. More particularly, the invention relates to a trigger group module pre-assembled with one or more trigger group components and adapted to be received in the frame of the firearm. The invention also relates to a method of installing trigger group components in a firearm.
Firearm firing mechanisms generally include a number of components that cooperate to hold a spring-loaded hammer in a cocked position and then selectively release the hammer. The firearm is fired or discharged when the force of the released hammer is applied, directly or through an intermediate device, to an ammunition cartridge loaded in the firearm. The components for holding the hammer in a cocked position and then releasing the hammer as desired may be referred to as a trigger group. In addition to the hammer itself, a trigger group generally includes a trigger component having a finger lever or trigger that a user pulls to release the hammer, and further includes a sear which may be a separate component or integrally formed with the trigger component. Some trigger groups also include other components such as a disconnector for example. The disconnector is used in semi-automatic firearms to catch the hammer as it rebounds after firing and to hold the hammer in a cocked position until the shooter can release the trigger and thereby reset the trigger group to the xe2x80x9cready to fire position.xe2x80x9d The disconnector is required for this function because semi-automatic firearms usually cycle so quickly that it is physically impossible for the shooter to release the trigger quickly enough after a discharge to allow the sear to recapture the hammer in the cocked position.
Both the hammer component and trigger component are commonly mounted for rotation in the firearm. The hammer is mounted on a hammer pin to facilitate the desired rotation, while the trigger component is mounted on a trigger pin. Each pin is retained in a respective pin receptacle formed in the firearm. Each such pin receptacle is defined by a first opening on one side of the firearm and a second opening on the opposite side of the firearm. A hammer spring is included in the trigger group to, among other things, bias the hammer forward to a striking position. The trigger component is also spring biased to provide resistance against pulling the trigger and to return the trigger after it has been pulled.
It may be desirable to modify or replace trigger group components in a firearm. This is particularly true for firearms used in competition. Such competition firearms may be fitted with special trigger group components designed to improve firearm performance or operational characteristics, or to suit the preferences of the particular user. Also, different competitions or firearm applications may require different trigger group characteristics. However, due to the relatively small components in the trigger group, the spring loading of components, the close tolerances between components, and the small area in the firearm allotted for trigger group components, a trigger group may commonly be installed only by a skilled gunsmith using specialized tools in order to ensure safe, proper, and reliable trigger group finctioning. Due to the difficulty in changing out trigger group components, it is common for many competition shooters to have several different complete firearms each with a different trigger group setup for a particular competition or portion of a competition. Maintaining several complete firearms greatly increases the cost of competitive shooting.
The present invention provides a trigger group module that is pre-assembled with the trigger group components and adapted to be mounted in a trigger group receiving area in place of the original equipment manufacturer (OEM) trigger group. The invention includes a special module housing and also includes the special housing pre-assembled with one or more trigger group components to form the self-contained trigger group module. The invention further includes methods for mounting or installing a trigger group in a firearm.
A module housing according to the invention is adapted to be inserted into an operating position in the trigger group receiving area of a firearm. The module housing includes at least one pin receiver defined by two openings formed in the module housing, one on each lateral side of the housing. In one form of the invention a module or temporary pin is received in the pin receiver and at least one trigger group component is mounted or supported for rotation on the module pin. In this form of the invention, the pin receiver is located on the module housing so as to align with a pin receptacle of the firearm when the module housing is in the operating position. That is, the two openings defining the pin receiver on the module housing are adapted to align with the openings on the firearm that define a pin receptacle for the firearm.
By locating the pin receiver in the module housing so as to align with a corresponding pin receptacle of the firearm when the module housing is in the operating position, the trigger group module and the trigger group components housed in the module housing may be readily supported by the OEM pin receptacle. The trigger group module, pre-assembled with one or more trigger group components, may be inserted to the operating position and then a permanent pin may be inserted or extended through the OEM pin receptacle and aligned trigger group component to support the trigger group component in the desired functional position in the firearm. The module housing and temporary pin hold the trigger group component in place while the module housing is being placed in the firearm. Once the module housing is inserted to the operating position, the module and associated trigger group components may be secured in place with the OEM pin receptacles and cooperating permanent pins. No modification to the frame of the firearm is required and no special skill or tools are required to install the self-contained, pre-assembled trigger group module.
One preferred form of the invention is adapted to be used with a firearm that includes a hammer pin receptacle and a trigger pin receptacle. The trigger group module for this firearm includes a first pin receiver and a second pin receiver. The first pin receiver aligns with the hammer pin receptacle of the firearm when the housing is in the operating position and the second pin receiver aligns with the trigger pin receptacle when the housing is in the operating position. To install this trigger group module, the original trigger group components are removed from the firearm together with any interfering components such as safety mechanisms for example, and then the pre-assembled trigger group module is placed in the operating position in the firearm. Once in the operating position, the hammer and trigger component may be supported for rotation from the openings defining the hammer pin receptacle and trigger pin receptacle, respectively. This support also holds the entire module in place in the firearm.
In one preferred form of the invention, each module pin comprises a temporary pin that is temporarily supported in the respective pin receiver of the module housing. These temporary pins may be held in place with a suitable retainer which may comprise simply a membrane or adhesive tape adhered to the outer surface of the housing so as to cover the pin receiver openings. In this temporary pin arrangement, the module may be installed by aligning the pin receivers on the housing with the firearm pin receptacles and then inserting a permanent pin into each pin receptacle. Inserting a permanent pin into one of the pin receptacle openings pierces or displaces the membranes holding the temporary pin in place and displaces the temporary pin through the opposite side of the housing and pin receptacle.
One preferred form of the invention includes a module housing in which one or more housing pin receiver openings align with one or more OEM pin receptacle openings, but the module includes permanent pins rather than temporary pins. In this embodiment of the invention, the pins included in the trigger group module are not displaced by permanent pins inserted through the OEM pin receptacle openings. However, caps, screws, pins, or other elements may be inserted into the OEM pin receptacle openings to cooperate with a trigger group module pin to retain the trigger group module in the operating position. For example, the module pins may be hollow and adapted to receive pins inserted through the OEM pin receptacle openings to retain the module and module components in the operating position.
In yet other forms of the invention, the module housing may include no pin receiver openings located to align with OEM pin receptacle openings when the trigger group module is in the operating position in the firearm frame. Rather, the trigger group component geometry may be completely changed from the OEM trigger group geometry. In these forms of the invention, the OEM pin receptacle openings may still be used to receive screws, pins, or other devices to secure the trigger group module in the operating position in the firearm frame.
A module housing according to the invention may also include a trigger component control feature that defines or sets either the forward most or rearward most position of the trigger component. Two different trigger component control features may be used to set both the forward most and rearward most position of the trigger component. The trigger component control feature setting the rearward most position of the trigger component provides overtravel control to minimize the amount of trigger movement possible after the hammer release point. The trigger component control feature setting the forward most position of the trigger component provides take-up control which minimizes the movement of the trigger required before reaching the hammer release point. A major advantage of the present invention is that by incorporating the overtravel and take-up features in the module housing, trigger overtravel and take-up may be modified without having to modify the frame of the firearm itself.
These and other features and advantages of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.